Coated cutting tool

Abstract

A coated cutting tool is provided. The cutting tool is CVD coated and has a substrate of cemented carbide, wherein a metallic binder in the cemented carbide includes Ni. The CVD coating has an inner layer of TiN and a subsequent layer of TiCN and a layer of Al2O3 located between the TiCN layer and an outermost surface of the coated cutting tool.

1 . A method of making a coated cutting tool, the method comprising chemical vapor deposition of a coating on a substrate, wherein said coating includes an inner layer of TiN, a subsequent layer of TiCN and a Al 2 O 3  layer located between the TiCN layer and an outermost surface of the coated cutting tool, wherein the substrate is made of cemented carbide composed of hard constituents in a metallic binder and wherein the metallic binder includes 60 to 90 wt % Ni, wherein the TiN layer is deposited on the cemented carbide substrate in two subsequent steps at a temperature of about 850-900° C. and a pressure of about 300-600 mbar: a first TiN deposition of TiN-1, followed by a second TiN deposition of TiN-2, the TiN-1 deposition being performed in a gas having 1-1.5 vol % TiCl 4  and H 2  and N 2 , wherein the volume ratio H 2 /N 2  is 0.05-0.18, and wherein the gas includes 0.5-1.5 vol % HCl, and the TiN-2 deposition is performed in a gas having 2-3 vol % TiCl 4  and H 2  and N 2 , wherein the volume ratio H 2 /N 2  is 0.8-2.5. 
     
     
         2 . The method of  claim 1 , wherein the layer of TiCN is deposited in two subsequent steps at a temperature of about 875-895° C. and a pressure of about 50-70 mbar: a first deposition of TiCN, followed by a second deposition of TiCN, the first TiCN deposition is performed in gas having 55-65 vol % H 2 , 35-40 vol % N 2 , 2.8-3.1 vol % TiCl 4  and 0.4-0.5 vol % CH 3 CN, and the second TiCN deposition is performed in a gas having 75-85 vol % H 2 , 6-9 vol % N 2 , 2.3-2.5 vol % TiCl 4 , 0.6-0.7 vol % CH 3 CN and 7-9 vol % HCl. 
     
     
         3 . The method of  claim 1 , wherein the method further comprises deposition of a layer of Al 2 O 3  between the TiCN layer and the outermost surface of the coated cutting tool, said deposition of Al 2 O 3  being performed in at least two steps, both steps at a temperature of 980-1020° C. and a pressure of 50-60 mbar, wherein a first step is performed in a gas composition of 1.1-1.3 vol % AlCl 3 , 4.5-5 vol % CO 2 , 1.6-2.0 vol % HCl and the rest H 2 , and wherein a subsequent second step is performed in a gas composition of 1.1-1.3 vol % AlCl 3 , 4.5-5 vol % CO 2 , 2.8-3.0 vol % HC1, 0.55-0.6 vol % H 2 S and the rest H 2 . 
     
     
         4 . The method of  claim 1 , wherein the metallic binder includes 10-20 wt % Fe, and/or 65-88 wt % Ni, and/or 3-8 wt % Co. 
     
     
         5 . The method of  claim 1 , wherein the metallic binder content in the cemented carbide is 3-20 wt %. 
     
     
         6 . A coated cutting tool comprising:
 a substrate; and   a coating, wherein the substrate is made of cemented carbide composed of hard constituents in a metallic binder and wherein said metallic binder comprises 60 to 90 wt % Ni, and wherein the coating includes an inner TiN layer, a TiCN layer and a A1203 layer located between the TiCN layer and an outermost surface of the coated cutting tool and, wherein the TiCN is composed of crystal grains and wherein the grain size of the TiCN layer as measured along a line in a direction parallel to the surface of the substrate at a position of 1 μm from the TiN layer is about 0.10-0.30 μm.   
     
     
         7 . The coated cutting tool of  claim 6 , wherein the metallic binder includes 10-20 wt % Fe, and/or 65-88 wt % Ni, and/or 3-8 wt % Co. 
     
     
         8 . The coated cutting tool of  claim 6 , wherein the metallic binder content in the cemented carbide is 3-20 wt %. 
     
     
         9 . The coated cutting tool of  claim 6 , wherein the thickness of the TiN layer is 0.3-1 μm deposited directly on the cemented carbide substrate. 
     
     
         10 . The coated cutting tool of  claim 6 , wherein the TiCN layer exhibits a texture coefficient TC(hkl), as measured by X-ray diffraction using CuKα radiation and θ-2θ scan, defined according to Harris formula 
       
         
           
             
               
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         where I(hkl) is the measured intensity (integrated area) of the (hkl) reflection, I 0 (hkl) is the standard intensity according to ICDD's PDF-card No 42-1489, n is the number of reflections, reflections used in the calculation are (1 1 1), (2 0 0), (2 2 0), (3 1 1), (3 3 1), (4 2 0), (4 2 2) and (5 1 1), wherein TC(4 2 2) is ≥3.5. 
       
     
     
         11 . The coated cutting tool of  claim 6 , wherein the thickness of the TiCN layer is 6-12 μm. 
     
     
         12 . The coated cutting tool of  claim 6 , wherein the CVD coating further includes one or more layers selected from TiN, TiCN, AlTiN, ZrCN, TiB 2 , Al 2 O 3 , or multilayers comprising of α-Al 2 O 3  and/or κ-Al 2 O 3 . 
     
     
         13 . The coated cutting tool of  claim 6 , wherein the total thickness of the CVD coating is 2-20 μm. 
     
     
         14 . The coated cutting tool of  claim 6 , wherein the Al 2 O 3  layer between the TiCN layer and an outermost surface of the coated cutting tool is an α-Al 2 O 3  layer. 
     
     
         15 . The coated cutting tool of  claim 14 , wherein said α-Al 2 O 3  layer exhibits a texture coefficient TC(hkl), as measured by X-ray diffraction using Cukα radiation and θ-274  scan, defined according to Harris formula where I(hkl) is the measured intensity (integrated area) of the (hkl) reflection,
 I 0 (hkl) is the standard intensity according to ICDD's PDF-card No. 00-010-0173, n is the number of reflections used in the calculation, and where the (hkl) reflections used are (1 0 4), (1 10), (1 1 3), (024), (1 1 6), (2 14), (3 0 0) and (0 0 12) 
 wherein 
 TC(0 0 12)≥6. 
 
     
     
         16 . The coated cutting tool of  claim 14 , wherein the α-Al 2 O 3  layer exhibits an intensity ratio I(0 0 12)/I(0 1 14) of ≥0.8. 
     
     
         17 . The coated cutting tool of  claim 6 , wherein the thickness of the Al 2 O 3  layer located between the TiCN layer and an outermost surface of the coated cutting tool is 4-8 μm.